1. Field of the Invention
The present invention relates to a film-forming method of forming a thin film on a substrate-to-be-processed. It particularly relates to a film-forming method of homogenizing a thin film formed on each substrate-to-be-processed when forming a thin film continuously on multiple substrates-to-be-processed.
2. Description of the Related Art
A plasma CVD (Chemical Vapor Deposition) apparatus forms a thin film on the surface of a substrate-to-be-processed by applying radio-frequency power between an upper electrode, which also functions as a showerhead which supplies a reaction gas to a processing chamber, and a lower electrode which also functions as a loading platform for loading substrates-to-be-processed such as semiconductor wafers. Sediment is left on inner walls, etc. of the processing chamber during this film-forming process. If this comes off, it causes particle contamination in the next film-forming process. For this reason, the processing chamber is cleaned periodically.
For such apparatuses, when a lot (one lot can be, for example, one cassette (25 wafers)) is processed continuously, the film-forming process and the cleaning process are repeated alternately. After maintenance of the apparatus is performed, until the result of a film quality inspection of wafer processing is obtained, a stand-by situation where no film forming is performed occurs between the lot processes.
The number of stand-by times shows a tendency to increase particularly as the number of semiconductor manufacturing plants which manufacture semiconductor devices with more different types in smaller lots increases, as a diameter of wafer becomes larger in recent years, and as semiconductor devices are more diversified.